Hi,

I’m working with the following model:

```
data{
int N;
vector[N] obs_times;
vector[N] t;
}
parameters{
real<lower=0> lambda;
}
model{
obs_times~exponential(lambda);
lambda~normal(0,5);
}
generated quantities{
//Draw survival function
vector[N] surv;
for(i in 1:N){
surv[i]=exp(-lambda*t[i]);
}
}
```

which I run as follows:

```
library(cmdstanr)
dat<-list(N=100,obs_times=data$x,t=seq(0,1.5,length=100))
mod<-cmdstan_model("surv_exp.stan")
fit<-mod$sample(data=dat,
chains=4,
parallel_chains=4)
```

I would like to extract “surv” values to make a plot. However, I found that “surv” values are not printed in the right order:

```
> fit$draws("surv",format="list")
# A draws_list: 1000 iterations, 4 chains, and 100 variables
[chain = 1]
$`surv[1]`
[1] 1 1 1 1 1 1 1 1 1 1
$`surv[2]`
[1] 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96 0.96
$`surv[3]`
[1] 0.92 0.92 0.93 0.93 0.91 0.92 0.92 0.92 0.92 0.92
$`surv[4]`
[1] 0.88 0.89 0.89 0.89 0.87 0.88 0.88 0.88 0.88 0.88
```

I would expect to the see the values ordered like this: 1, 0.96, 0.92, 0.88…

If I convert the cmdstanr object into an rstan object and then extract “surv” values, then the values are printed in the right order:

```
library(rstan)
stanfit <- rstan::read_stan_csv(fit$output_files())
post<-extract(stanfit)
post$surv[1:2,]
iterations [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
[1,] 1 0.960775 0.923088 0.886879 0.852091 0.818668 0.786555 0.755702 0.726060
[2,] 1 0.951013 0.904426 0.860121 0.817987 0.777916 0.739809 0.703568 0.669102
iterations [,10] [,11] [,12] [,13] [,14] [,15] [,16] [,17] [,18]
[1,] 0.697580 0.670217 0.643927 0.618669 0.594402 0.571086 0.548685 0.527163 0.506484
[2,] 0.636325 0.605154 0.575509 0.547317 0.520505 0.495008 0.470759 0.447698 0.425767
```

How can I change the way the values are printed?

data_surv.csv (1.8 KB)